LibJS/Bytecode: Don't replace the entry block in MergeBlocks

The entry block must stay in place, although it's okay to merge stuff into it. This fixes 4 test262 tests and brings us to parity with optimization disabled. :^)
Author: https://github.com/awesomekling Commit: https://github.com/SerenityOS/serenity/commit/acd29e064c Pull-request: https://github.com/SerenityOS/serenity/pull/23462 Reviewed-by: https://github.com/Hendiadyoin1
2024-03-03 19:04:55 +01:00 · 2024-03-03 19:04:55 +01:00 · acd29e064c · 2024-07-17 17:40:13 +09:00
commit acd29e064c
parent 5b29974bfa
1 changed files with 2 additions and 1 deletions
--- a/Userland/Libraries/LibJS/Bytecode/Pass/MergeBlocks.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Pass/MergeBlocks.cpp
@ -36,7 +36,8 @@ void MergeBlocks::perform(PassPipelineExecutable& executable)
        if (entry.key->terminator()->type() != Instruction::Type::Jump)
            continue;

-        {
+        // NOTE: We can't replace the first block in a function, as it's the entry block.
+        if (entry.key != executable.executable.basic_blocks.first()) {
            InstructionStreamIterator it { entry.key->instruction_stream() };
            auto& first_instruction = *it;
            if (first_instruction.type() == Instruction::Type::Jump) {